zein

Zein is a class of prolamin storage proteins found in the seed (endosperm) of maize (corn). It comprises several fractions, including alpha-, beta-, gamma-, and delta-zein, with alpha-zein forming the major portion. Zein is rich in glutamine and proline and is highly hydrophobic. It is insoluble in water but dissolves in aqueous alcohols and certain organic solvents, enabling its use in film formation and coatings.

Biochemically, zeins are seed storage proteins that accumulate in the corn endosperm and contribute to the kernel’s protein content. They form dense protein networks that can be processed into transparent, edible films. Zein films are noted for good barrier properties against oxygen and moisture, strength, and gloss, making them attractive for packaging, coatings for foods and candies, and controlled-release matrices in pharmaceuticals.

Nutrition-wise, zein has a low content of essential amino acids, particularly lysine and tryptophan, which limits its value as a complete protein for human and animal diets. Traditional maize varieties therefore have a relatively poor essential amino acid profile. Breeding efforts, such as quality protein maize, aim to improve nutritional quality by reducing zein content and increasing lysine availability.

Applications extend beyond food and nutrition. Zein is used as a coating and film-forming agent in edible coatings and as a carrier in drug delivery systems and cosmetics. It is also explored as a biodegradable polymer for environmentally friendly packaging and packaging composites, often used in blends with other polymers to tailor mechanical and barrier properties.